Typical jumper cables used in vehicles for emergency start only act as power switches to turn on/off the power supply, and are therefore of function singleness. In addition, none of the conventional jumper cables includes a display module. As a result, there is a case that the vehicle battery is in a good condition and the vehicle battery is able to still work well, but the conventional jumper cables cannot identify the actual status. Accordingly, there is a desire in the art to design an improved jumper cable.